diff --git a/craft_application/errors.py b/craft_application/errors.py
index ea2c6db8..e4ea0c0d 100644
--- a/craft_application/errors.py
+++ b/craft_application/errors.py
@@ -19,7 +19,7 @@
 """
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, TypeVar
+from typing import TYPE_CHECKING, Self, TypeVar
 
 from craft_cli import CraftError
 
@@ -76,7 +76,7 @@ def from_pydantic(
         *,
         file_name: str = "yaml file",
         **kwargs: str | bool | int,
-    ) -> _ErrType:
+    ) -> Self:
         """Convert this error from a pydantic ValidationError.
 
         :param error: The pydantic error to convert
@@ -91,12 +91,12 @@ class PartsLifecycleError(CraftError):
     """Error during parts processing."""
 
     @classmethod
-    def from_parts_error(cls: type[_ErrType], err: craft_parts.PartsError) -> _ErrType:
+    def from_parts_error(cls: type[_ErrType], err: craft_parts.PartsError) -> Self:
         """Shortcut to create a PartsLifecycleError from a PartsError."""
         return cls(message=err.brief, details=err.details, resolution=err.resolution)
 
     @classmethod
-    def from_os_error(cls: type[_ErrType], err: OSError) -> _ErrType:
+    def from_os_error(cls: type[_ErrType], err: OSError) -> Self:
         """Create a PartsLifecycleError from an OSError."""
         message = f"{err.filename}: {err.strerror}" if err.filename else err.strerror
         details = err.__class__.__name__
diff --git a/craft_application/models/base.py b/craft_application/models/base.py
index f8dbe230..1711cb7f 100644
--- a/craft_application/models/base.py
+++ b/craft_application/models/base.py
@@ -16,7 +16,7 @@
 """Base pydantic model for *craft applications."""
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Any, TypeVar
+from typing import TYPE_CHECKING, Any, Self, TypeVar
 
 import pydantic
 import yaml
@@ -54,7 +54,7 @@ def marshal(self) -> dict[str, str | list[str] | dict[str, Any]]:
         return self.dict(by_alias=True, exclude_unset=True)
 
     @classmethod
-    def unmarshal(cls: type[_ModelType], data: dict[str, Any] | Any) -> _ModelType:
+    def unmarshal(cls: type[_ModelType], data: dict[str, Any]) -> Self:
         """Create and populate a new model object from dictionary data.
 
         The unmarshal method validates entries in the input dictionary, populating
@@ -69,7 +69,7 @@ def unmarshal(cls: type[_ModelType], data: dict[str, Any] | Any) -> _ModelType:
         return cls(**data)
 
     @classmethod
-    def from_yaml_file(cls: type[_ModelType], path: pathlib.Path) -> _ModelType:
+    def from_yaml_file(cls: type[_ModelType], path: pathlib.Path) -> Self:
         """Instantiate this model from a YAML file."""
         with path.open() as file:
             data = safe_yaml_load(file)
diff --git a/craft_application/util/error_formatting.py b/craft_application/util/error_formatting.py
index 6af6fa48..49866823 100644
--- a/craft_application/util/error_formatting.py
+++ b/craft_application/util/error_formatting.py
@@ -101,8 +101,7 @@ def _format_pydantic_error_location(loc: Iterable[Union[str, int]]) -> str:
     loc = ".".join(loc_parts)
 
     # Filter out internal __root__ detail.
-    loc = loc.replace(".__root__", "")
-    return loc
+    return loc.replace(".__root__", "")
 
 
 def _format_pydantic_error_message(msg: str) -> str: